This invention relates to a device for dispensing chemical reagents into water test samples so that such samples may be chemically analyzed.
Chemical reagents are widely employed in the photometric testing of water for constituents such as chlorine. A number of devices are available for dispensing a single dosage of chemical reagent into the test sample. Typically, the dispensing device is first attached to a bottle containing the chemical reagent. The dispenser is then inverted and positioned over a test tube, cuvette or other receptacle containing the test sample. The mechanism is operated, normally by depressing a plunger, to dispense the chemical reagent into the test sample.
Known reagent dispensers exhibit a number of disadvantages. Although, cuvettes and other test sample holders come in a wide variety of shapes and sizes, most available dispensers are designed for use with only a single type of holder or, at most, a limited number of holders. It can also be difficult to accurately orient the dispenser over the holder so that dispensing is performed cleanly and efficiently. The lower dispensing end of the device is apt to accidentally dip into the test sample. This can contaminate the sample and foul or clog the dispenser.
Conventional reagent dispensers also employ a housing that is not optimally sealed. As a result, when the dispenser is operated, powder reagent residue tends to collect along the dispenser shaft and enter the housing. This also tends to foul the dispensing device and can cause the apparatus to malfunction.
One currently available reagent dispenser features an O-ring spring plunger operation. This mechanism does not feature an optimally positive, accurate and efficient dispensing operation.
It is therefore an object of the present invention to provide a hand held device for simply, accurately and efficiently dispensing a single dosage of chemical reagent into a test sample.
It is a further object of this invention to provide a dispenser that is quickly, conveniently and effectively interengagable with both a threaded bottle containing reagent and a holder that accommodates a test sample.
It is a further object of this invention to provide a universal reagent dispenser that is effective for use with virtually all sizes and shapes of test sample holders.
It is a further object of this invention to provide a chemical reagent dispenser that avoids contaminating the sample being tested.
It is a further object of this invention to provide a chemical reagent dispenser that resists fouling, clogging and malfunctioning.
It is a further object of this invention to provide a universal reagent dispenser that avoids accidental spilling of the chemical reagent.
It is a further object of this invention to provide a chemical reagent dispenser featuring an improved positive spring operation.
It is a further object of this invention to provide a chemical reagent dispenser that accurately, reliably and efficiently delivers a single dosage of a chemical substance to a cuvette, test tube or other container holding a test sample.
This invention features a single dosage, universal chemical reagent dispenser including a dispenser body having an inlet that is communicably interengagable with a supply of reagent and an axially offset outlet that is communicably interengagable with a test sample holder. There is a spring loaded reciprocating plunger mounted slidably within a cavity in the dispenser body between the inlet and the outlet. The plunger carries an actuator member externally of the dispenser body. A single dosage chemical accommodating compartment is formed through the plunger. A helical compression spring urges the plunger into a first position wherein the plunger compartment is communicably aligned with the inlet such that a single dosage of chemical reagent is delivered into the compartment. Depressing the plunger actuator member causes the plunger to slide through the dispenser body against the spring until the plunger compartment communicates with the offset outlet. As a result, the single dosage of chemical reagent is dispensed through the outlet into the test holder that is engaged with the outlet.
In a preferred embodiment, the inlet includes thread for operably interengaging corresponding threads carried by a bottle or other chemical reagent container. An annular seal may be disposed between the mouth of the reagent container and the inlet of the dispenser body. The outlet may include a plurality of concentric, stepped receptacles. Each receptacle respectively interengages one or more corresponding test sample holders. The dispenser body may include an upper passageway segment that is communicably connected between the inlet and the plunger compartment and an offset lower passageway segment that is communicably connected between the plunger compartment and the outlet.
The plunger may include a shaft-like plunger member that is longitudinally slidable through the channel in the dispenser body. The plunger shaft may include a proximal end that extends outwardly from the body and is attached to the actuator member. The actuator member may comprise a button or tab. The distal end of the shaft may include a recess that receives one end of the spring. The opposite end of the spring may interengage an inside wall of the dispenser body.
The plunger shaft may further include a circumferential groove that accommodates an annular seal. The seal prevents residual chemical reagent from migrating along the shaft between the seal and the actuator member. This reduces fouling between the shaft and the dispenser body and resultant malfunctioning of the device. The plunger shaft may also include an elongate longitudinal notch that is interengaged by a indexing element, set screw, detent or other element carried within the dispenser body. This limits movement of the plunger outwardly from the dispenser body and prevents unintended removal of the plunger from the body. It also orients the plunger properly within the channel such that the compartment is alignable with the inlet and the outlet when the plunger is in the first and second positions respectively.
A closure or cap may be attached to the dispenser. The closure is selectively interengagable with the outlet to close the outlet when the dispenser is not in use. The lower passageway may include a sharp edge opening to prevent buildup of channel reagent in the lower passageway.